Feedstuffs for ruminants

ABSTRACT

The present invention aims to provide a technique for preparing feedstuffs for ruminants with high nutritional value or feed efficiency. 
     A process for preparing a feedstuff for ruminants of the present invention comprises: suspending a lignocellulosic material as a raw material in a liquid to give a pulp; processing the resulting pulp in a pressure type solid-liquid separator; and preparing a feedstuff containing the pulp subjected to solid-liquid separation.

TECHNICAL FIELD

The present invention relates to feedstuffs for ruminants.

BACKGROUND ART

Generally in the field of livestock farming, concentrate feedstuffs ofhigh nutritional value are often used in combination with roughagefeedstuffs such as forages in order to increase milk production or toincrease weight gain in livestock.

Concentrate feedstuffs are rich in easily digestible carbohydrates(starch and the like) such as corn, while roughage feedstuffs mainlyinclude dried forages (hay, straw), early harvested and fermented (i.e.,ensiled) forages and the like.

Ruminants can ingest and digest roughage feedstuffs because they have arumen (first stomach). The rumen occupies the largest volume among themultiple stomachs of ruminants, and contains much microorganisms (i.e.,ruminal microorganisms) capable of degrading hard-to-digestpolysaccharides such as celluloses and hemicelluloses in roughagefeedstuffs (i.e., ruminal fermentation).

However, celluloses and hemicelluloses in roughage feedstuffs are oftenbound to lignins and exist as lignin-cellulose complexes andlignin-hemicellulose complexes, respectively. Such complexes may not bedegraded sufficiently via ruminal fermentation so that roughagefeedstuffs had the problem that they tended to be insufficient in feedefficiency. Moreover, an increase in undigested materials was consideredto be environmentally undesirable because it leads to an increase infeces.

Furthermore, some forages contain much nitrate nitrogen, and ruminantshaving ingested them may suffer from various types of nitrite poisoning.Nitrite poisoning occurs when nitrous acid produced in vivo from nitratenitrogen in ingested forages combines with the oxygen carrier hemoglobinin the blood to impede hemoglobin from accepting oxygen. Severe cases ofnitrite poisoning cause asphyxia, which may result in sudden death ofruminants or a decrease in milk production or the like symptoms in dairycattle.

In addition, the supply of roughage feedstuffs is unstable because it issusceptible to the harvest yield or crop yield of forages. Especially,Japan mostly relies on imported roughage feedstuffs, which are generallysubject to significant price variation or may be difficult to importdepending on circumstances in exporting countries, thereby putting asqueeze on livestock farmers.

Thus, it would be desirable to provide inexpensive and stably availablefeedstuffs for ruminants as alternative to forages, that achieve a highfeed efficiency and are not responsible for diseases such as nitritepoisoning.

In this connection, concentrate feedstuffs rich in easily digestiblecarbohydrates (starch) are typically combined with roughage feedstuffsto increase the nutrient levels in feedstuffs. To maintain milkproduction in dairy livestock or to maintain weight gain in livestockfor meat, feed intake must also be increased because the rate ofincrease in the energy required to increase milk production or weightgain exceeds the rate of increase in feed intake. However, carbohydratessuch as starch in concentrate feedstuffs may cause a sudden drop of pHin the first stomach (rumen), resulting in ruminal acidosis. Ruminalacidosis is one of ruminant diseases caused by a sudden intake ofgrains, concentrate feedstuffs, fruits or the like rich incarbohydrates. Ruminal acidosis is characterized by the growth ofgram-positive lactate-producing bacteria, especially Streptococcus bovisand microorganisms of the genus Lactobacillus and the abnormalaccumulation of lactic acid or volatile fatty acids (VFAs) in the rumen,whereby the ruminal pH drops (to 5 or less). This results in a decreaseor disappearance of protozoa and certain types of bacteria in the rumen.In particular, acute acidosis is very critical because it leads tocongestion of the rumen or dehydration (a shift of a lot of body fluidsinto the stomach as a result of an increases in the osmotic pressure inthe stomach lumen), finally coma or death.

To prevent ruminal acidosis, it is important to avoid sudden changes infeed formulations, thereby stabilizing ruminal fermentation and reducingpH variations. It is also important to provide feedstuffs that stimulateadequate rumination to promote salivation because saliva contains sodiumbicarbonate contributing to pH adjustment. However, feedstuffs having alow nutritional value in fear of ruminal acidosis may cause a lack ofenergy and a decrease in milk production.

Feedstuffs for preventing ruminal acidosis are disclosed in patentliterature 1, which describes powdery/particulate molasses feedstuffsconsisting of a mixture containing 5 to 60 parts by weight of wastemolasses per 100 parts by weight of beet pulp. On the other hand, patentliterature 2 discloses feedstuffs for ruminants comprising 80% by weightor more of a cellulose and/or hemicellulose on a dry solids basis, whilepatent literature 3 discloses livestock feedstuffs obtained by applyinga high impact force to a wood raw material to break up it intomicroparticles.

CITATION LIST Patent Literatures

-   PTL 1: JPA2006-174796-   PTL 2: JPA2011-082381-   PTL 3: JPA2012-105570

SUMMARY OF INVENTION Technical Problem

However, the powdery/particulate molasses feedstuffs of patentliterature 1 consisting of a mixture of beet pulp and waste molassesdescribed above were not sufficient in feed efficiency such asdigestibility. On the other hand, the feedstuffs described in patentliterature 2 or patent literature 3 were poor in the effect ofstimulating the first stomach (rumen) of ruminant livestock to promoterumination (mechanical effect) and inferior in feeding preference.

Thus, the present invention aims to provide a technique for preparingfeedstuffs for ruminants with high nutritional value or feed efficiency.Especially, the present invention aims to provide feedstuffs having ahigh mechanical effect for promoting rumination without causing ruminalacidosis while they also have the economic advantages that they can bestably supplied at low cost without any possibility of adverse influencesuch as nitrite poisoning when compared with forages. Further, thepresent invention also aims to develop those feedstuffs for whichruminants show high preference.

Solution to Problem

As a result of careful studies about the problems described above, theinventors of the present invention accomplished the present invention onthe basis of the finding that the problems described above can besurprisingly solved by subjecting a pulp suspension of a lignocellulosicmaterial in a liquid to solid-liquid separation.

(1) A process for preparing a feedstuff for ruminants, comprising:suspending a lignocellulosic material as a raw material in a liquid togive a pulp; subjecting the resulting pulp to solid-liquid separation ina pressure type solid-liquid separator; and preparing a feedstuffcontaining the pulp subjected to solid-liquid separation.(2) The process of (1) wherein the pulp has a water content of 45% bymass or more and less than 80% by mass after it has been processed in asolid-liquid separator.(3) The process of (1) or (2) wherein the lignocellulosic material isderived from a wood resource.(4) The process of any one of (1) to (3) wherein the pulp is a kraftpulp.(5) The process of any one of (1) to (4) wherein the solid-liquidseparator is a screw press and/or filter press.(6) The process of any one of (1) to (5), further comprising drying thepulp processed in a solid-liquid separator to a water content of 15% orless.(7) The process of any one of (1) to (6), comprising solid-liquidseparation in multiple stages using a solid-liquid separator.(8) The process of (7), comprising a first stage of solid-liquidseparation until the water content of the pulp reaches 50 to 75% bymass.(9) The process of any one of (1) to (6), comprising solid-liquidseparation using a paper machine or pulp machine.(10) The process of (9) wherein the pulp subjected to solid-liquidseparation using a paper machine or pulp machine has a water content of15 to 35% by mass.(11) The process of any one of (1) to (10), further comprisingpelletizing the pulp subjected to solid-liquid separation.(12) The process of (11) wherein the pelletized pulp has a water contentof 15% by mass or less.(13) The process of (11) or (12) wherein the pulp has a water content of15 to 30% by mass before it has been pelletized.

Advantageous Effects of Invention

The present invention makes it possible to obtain feedstuffs for whichruminants show high preference and having the effect of stimulating thefirst stomach (rumen) of ruminant livestock to promote rumination(mechanical effect). Especially, the feedstuffs of the present inventioncan prevent ruminal acidosis or nitrite poisoning or the like becausethe amount of conventional concentrate feedstuffs or forages used can bereduced. Further, the feedstuffs for ruminants according to the presentinvention can be stably supplied at low cost because they can beprepared from plant raw materials such as wood. In addition, they alsohave high transportability.

DESCRIPTION OF EMBODIMENTS

The feedstuffs for ruminants according to the present invention areapplied to ruminants. Ruminants include, for example, cattle such asdairy cattle and beef cattle, sheep, goats and the like. The time whenruminants are fed with the feedstuffs of the present invention, i.e.,the age, size, health condition or the like of the ruminants to be fedis not specifically limited, and may be from suckling calves havingfinished the period during which they are fed with a milk replacer toadult cattle.

The feedstuffs for ruminants according to the present invention comprisea pulp prepared from a lignocellulosic raw material and processed in asolid-liquid separator. The present invention comprises the steps ofpulping a lignocellulosic raw material in a liquid, then washing theresulting pulp with water and dewatering it, wherein the pulp used inthe present invention is controlled at a water content in a pressuretype solid-liquid separator during the dewatering step. The watercontent here is preferably 45% by mass or more and less than 80% bymass. If the water content is less than 45% by mass, water isexcessively removed and molded products obtained from the pulp become sohard that digestibility decreases. If the water content is 80% by massor more, the pulp cannot be molded and transportability decreases. Itshould be noted that the water content may be controlled to less than80% by mass in a solid-liquid separator and then further lowered by airdrying.

Further, preferred embodiments of the present invention can comprisesolid-liquid separation in multiple stages using a solid-liquidseparator. An illustrative embodiment can comprise a first stage ofsolid-liquid separation during which the water content (moisturecontent) of the pulp reaches 50 to 75% by mass, or a first stage ofsolid-liquid separation during which the water content may be lowered to55 to 70% by mass or 60 to 65% by mass.

Pressure type solid-liquid separators that can preferably be usedinclude screw presses, filter presses and the like, which are typicallyalso used as washers during pulp producing processes.

Alternatively, the present invention can comprise solid-liquidseparation using a paper machine or pulp machine. For example, the watercontent of the pulp can be adjusted to 15 to 35% by mass duringsolid-liquid separation using a paper machine, or the water content ofthe pulp may be lowered to 16 to 30% by mass or 17 to 25% by mass byusing a paper machine. In this connection, the pulp subjected tosolid-liquid separation using a paper machine or pulp machine can be apulp sheet having a basis weight of 100 to 2000 g/cm³. Typically, apaper machine or pulp machine comprises a wire part, a press part, and adryer part, wherein a pulp suspension is suppled to an endless wire toform a pulp sheet in the wire part, then the pulp sheet is transportedon a press felt and further dewatered through a press nip in the presspart, and the pulp sheet is dried while it is transported on a canvas inthe dryer part.

The feedstuffs for ruminants according to the present invention can usepulps prepared by various known pulping processes. For example, bothmechanical and chemical pulps can be applied. Mechanical pulps includegroundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanicalpulp (TMP), chemithermomechanical pulp (CTMP) and the like. Chemicalpulps include kraft pulp (KP), dissolving kraft pulp (DKP), sulfite pulp(SP), dissolving sulfite pulp (DSP) and the like. Further, both bleachedand unbleached pulps can be used.

In the feedstuffs for ruminants according to the present invention, thepulp may consist of a single pulp or may be a mixture of multiple pulps.For example, a mixture of two or more of chemical pulps (hardwood kraftpulp, softwood kraft pulp, dissolving hardwood kraft pulp, dissolvingsoftwood kraft pulp), or mechanical pulps (groundwood pulp, refinergroundwood pulp, thermomechanical pulp, chemithermomechanical pulp)derived from different sources or prepared by different processes may beused.

Wood raw materials that can be used include, for example, hardwoods,softwoods, trysting trees, bamboo, kenaf, bagas and empty fruit brunchesobtained after palm oil extraction. Specifically, examples of hardwoodsinclude Fagus crenata, Tilia japonica, Betula platyphylla, Populus,Eucalyptus, Acacia, oaks, Acer pictumn subsp. mono, Kalopanarseptemlobus, elms, Paulownia tomentosa, Mangolia obovata, willows,Kalopanax pictus Nakai, Quercus phillyraeoides, Quercus serrata, Quercusacutissimna, Aesculus turbinata, Zelkova serrata, Betula grossa, Cornuscontroversa, Fraxinus lanuginosa f. serrata and the like. Examples ofsoftwoods include Cryptomeria japonica, Picea jezoensis, Larixkaempferi, Pinus thunbergii, Abies Sachalinensis, Pinus parviflora var.parviflora, Taxus cuspidata, Thuja standishii, Picea lorano, Piceaalcokiana, Podocarpus macrophyllus, Abies firma, Chamaecyparis pisifera,Pseudotsuga japonica, Thujopsis dolabrata, Thujopsis dolabrata var.hondae, Tsuga sieboldii, Tsuga diversifolia, Chamaecyparis obtusa, Taxuscuspidata, Cephalotaxus harringtonia, Picea jezoensis var. hondoensis,yellow cedar (Cupressus nootkatensis), Lawson's cypress (Chamaecyparislawsoniana), Douglas fir (Pseudotsuga menziesii), Sitka spruce (Piceasitchensis), Pinus radiata, eastern spruce, eastern white pine, westernlarch, western fir, western hemlock, Larix occidentalis and the like.

Kraft Pulp

In preferred embodiments, the pulp of the present invention comprises akraft pulp, especially preferably a wood-derived kraft pulp. Further,the pulp of the present invention preferably has a kappa number of 5 ormore and less than 15, and preferably comprises an oxygen-delignifiedkraft pulp.

For preparing a kraft pulp from wood chips, the wood chips are fed intoa digester together with a cooking liquor and subjected to kraftcooking. Alternatively, they may be subjected to a modified kraftcooking process such as MCC, EMCC, ITC, Lo-solids or the like process.Further, the cooking system is not specifically limited, includingone-vessel liquor phase, one-vessel steam/liquor phase, two-vesselliquor/steam phase, two-vessel liquor phase or the like system. Thus,the step of impregnating wood chips with an aqueous alkaline solutionand holding them described herein may be provided separately fromconventional equipment or sites intended for penetration of cookingliquors. Preferably, the unbleached cooked pulp is washed in a washersuch as a diffusion washer after the cooking liquor has been extracted.

The kraft cooking process can be performed by loading a pressure vesselwith pre-hydrolyzed wood chips and a kraft cooking liquor wherein theshape or size of the vessel is not specifically limited. The ratio ofthe chemical liquid to the wood chips can be, for example, 1.0 to 5.0L/kg, preferably 1.5 to 4.5 L/kg, more preferably 2.0 to 4.0 L/kg.

In the present invention, an alkaline cooking liquor containing 0.01 to1.5% by mass of a quinone compound based on the bone dry weight of thechips may be added to the digester. If the amount of the quinonecompound added is less than 0.01% by mass, it is too little to reducethe kappa number of the pulp after cooking so that the relationshipbetween the kappa number and the pulp yield cannot be improved.Moreover, reduction of residues and reduction in viscosity loss are alsoinsufficient. Even if the amount of the quinone compound added exceeds1.5% by mass, however, neither further reduction in the kappa number ofthe pulp after cooking nor improvement in the relationship between thekappa number and the pulp yield is observed.

The quinone compound used is a quinone compound, hydroquinone compoundor a precursor thereof known as the so-called digestion aid, and atleast one compound selected from these members can be used. Thesecompounds include, for example, quinone compounds such asanthraquinones, dihydroanthraquinones (e.g., 1,4-dihydroanthraquinone),tetrahydroanthraquinones (e.g., 1,4,4a,9a-tetrahydroanthraquinone,1,2,3,4-tetrahydroanthraquinone), methylanthraquinones (e.g.,1-methylanthraquinone, 2-methylanthraquinone),methyldihydroanthraquinones (e.g., 2-methyl-1,4-dihydroanthraquinone),and methyltetrahydroanthraquinones (e.g.,1-methyl-1,4,4a,9a-tetrahydroanthraquinone,2-methyl-1,4,4a,9a-tetrahydroanthraquinone); hydroquinone compounds suchas anthrahydroquinones (typically 9,10-dihydroxyanthracene),methylanthrahydroquinones (e.g., 2-methylanthrahydroquinone),dihydroanthrahydroanthraquinones (e.g.,1,4-dihydro-9,10-dihydroxyanthracene) or alkali metal salts thereof(e.g., the disodium salt of an anthrahydroquinone, the disodium salt of1,4-dihydro-9,10-dihydroxyanthracene); and their precursors such asanthrones, anthranols, methylanthrones, and methylanthranols. Theseprecursors can be converted into quinone compounds or hydroquinonecompounds under cooking conditions.

The cooking liquor preferably has an active alkali charge (AA) of 16 to22% by mass based on the bone dry weight of wood chips when the woodchips are derived from softwoods. If the active alkali charge is lessthan 16% by mass, lignins or hemicelluloses are not sufficientlyremoved, but if it exceeds 22% by mass, the yield decreases or thequality decreases. As used herein, the active alkali charge refers tothe total charge of NaOH and Na₂S, expressed as the charge of Na₂Oobtained by multiplying the charge of NaOH by 0.775 and the charge ofNa₂S by 0.795 to convert them into the corresponding charges of Na₂O.Further, it preferably has a sulfidity in the range of 20 to 35%. If thesulfidity is in the range of less than 20%, delignification slows down,the pulp viscosity decreases, and the residue content increases.

The kraft cooking process preferably takes place in the temperaturerange of 120 to 180° C., more preferably 140 to 160° C. If thetemperature is too low, delignification (reduction in kappa number) isinsufficient, but if the temperature is too high, the degree ofpolymerization (viscosity) of celluloses decreases. As used herein, thecooking time refers to a time period after the cooking temperaturereaches the maximum temperature before the temperature begin to drop,and preferably ranges from 60 minutes or more to 600 minutes or less,more preferably 120 minutes or more to 360 minutes or less. If thecooking time is shorter than 60 minutes, pulping does not proceed, butif it exceeds 600 minutes, the pulp production efficiency decreases, andtherefore, either case is not preferred.

In the kraft cooking process according to the present invention, theprocess temperature and the process time can be selected based on theH-factor (Hf). The H-factor is an indicator of the total amount of heatgiven to a reaction system during cooking and expressed by the equationbelow. The H-factor is calculated by integration over time from theinstant when chips and water are mixed to the end of cooking.

Hf=∫exp(43.20−16113/T)dt

wherein T represents the absolute temperature at a given instant.

In the present invention, the unbleached pulp obtained after cooking canbe subjected to various processes, as appropriate. For example, theunbleached pulp obtained after kraft cooking can be subjected to ableaching process.

The pulp obtained after kraft cooking can be subjected to an oxygendelignification process. A known medium consistency method or highconsistency method can be directly applied for the oxygendelignification process used in the present invention. Preferably, themedium consistency method is performed at a pulp consistency of 8 to 15%by mass, and the high consistency method is performed at 20 to 35% bymass. Alkalis that can be used in the oxygen delignification processinclude sodium hydroxide and potassium hydroxide, and oxygen gases thatcan be used include oxygen from cryogenic separation, oxygen from PSA(Pressure Swing Adsorption), oxygen from VSA (Vacuum Swing Adsorption)and the like.

Reaction conditions for the oxygen delignification process include, butare not specifically limited to, an oxygen pressure of 3 to 9 kg/cm²,more preferably 4 to 7 kg/cm², an alkali charge of 0.5 to 4% by mass, atemperature of 80 to 140° C., a process time of 20 to 180 minutes, andother known conditions. It should be noted that the oxygendelignification process may be performed multiple times in the presentinvention.

When the kappa number is to be further reduced or the brightness is tobe further improved, the oxygen-delignified pulp is then sent to, forexample, a washing step in which it is washed, and then sent to amultistage bleaching step in which it can be subjected to a multistagebleaching process. The multistage bleaching process in the presentinvention preferably includes, but not specifically limited to, the useof a known bleaching agent such as an acid (A), chlorine dioxide (D), analkali (E), oxygen (O), hydrogen peroxide (P), ozone (Z), a peracid orthe like in combination with a bleaching aid. For example, a multistagebleaching sequence is preferably used, comprising a first stage using achlorine dioxide bleaching stage (D) or an ozone bleaching stage (Z), asecond stage using an alkali extraction stage (E) or a hydrogen peroxidestage (P), and a third and the subsequent stages using chlorine dioxideor hydrogen peroxide. The number of stages subsequent to the secondstage is not specifically limited either, but the total number of stagesis preferably at most three or four to avoid adverse effects on energyefficiency, productivity and the like. Further, a chelating agenttreatment stage using ethylenediaminetetraacetic acid (EDTA),diethylenetriaminepentaacetic acid (DTPA) or the like may be insertedinto the multistage bleaching process.

The feedstuffs for ruminants according to the present invention may havea pulp content of 100%, but may also contain other feedstuff componentsto improve nutrition or feeding preference. In the latter case, the pulpcontent is preferably 80% by weight or more, more preferably 90% byweight or more based on the total solids content of the feedstuffs.Other feedstuff components include roughage feedstuffs (e.g., forages),concentrate feedstuffs (e.g., grains such as corn and wheat, beans suchas soybean), wheat bran, rice bran, soy pulp, proteins, fats, vitamins,minerals and the like as well as additives (preservatives, colorants,perfumes, etc.) and the like. These other feedstuff components may bemixed with pulp during compression molding.

The feedstuffs for ruminants according to the present inventionpreferably have a water content of 15% by mass or less. When the watercontent is 15% by mass or less, transportability is improved wherebymicrobial corrosion can be reduced.

In the present invention, the pulp subjected to solid-liquid separationmay be pelletized. Pelletization improves transportability, therebyproviding easy-to-handle feedstuffs. In preferred embodiments, thepelletized pulp has a water content of 15% by mass or less, wherebymicrobial corrosion can be readily reduced even after long-term storage.Further in preferred embodiments, the water content of the pulp beforepelletization is 15 to 30% by mass, more preferably 16 to 25% by mass.If the water content is in such a range, the pulp can be easilypelletized and an efficient process is achieved because the pulp can bedried by the heat used for pelletization.

EXAMPLES

The following examples further illustrate the present invention, but thepresent invention is not limited to these examples. It should be notedthat the % values as used herein are based on weight unless otherwisespecified, and the numerical ranges are described to include theirendpoints.

Experiment 1: Preparation of Feedstuffs Using Pulps as Raw Materials

<Sample 1-1: Compressed Kraft Pulp>

Eucalyptus wood chips were used to prepare a kraft pulp in a liquid.First, eucalyptus wood chips (in an amount equivalent to 300 g on a bonedry basis) were subjected to kraft cooking in an autoclave under theconditions: an active alkali charge of 13.0%, a sulfidity of 25%, and anH-factor of 830, to give an unbleached kraft pulp (kappa number: 16.7,brightness: 30.3%). The pulp was washed with tap water and thencentrifuged to remove water, thereby giving a pulp having a consistencyof 30%.

The resulting kraft pulp was adjusted to a consistency of 10%, and thensubjected to oxygen delignification under the conditions: an O₂ chargeof 18 kg/t and a sodium hydroxide charge of 23 kg/t, at 100° C. for 90minutes to give an oxygen-delignified pulp (kappa number: 8.5, ISObrightness: 49.3%). The resulting pulp was washed with tap water untilit reached pH 8.0 or less, and then centrifuged to remove water. Thiswas followed by disintegration to give an oxygen-delignified pulp havinga pulp consistency of 20.6%.

The resulting oxygen-delignified pulp was subjected to solid-liquidseparation by compression in a screw press to give a compressed kraftpulp having a water content of 72.1%.

This compressed kraft pulp was placed in a rectangular tray (externaldimensions: 255 mm×320 mm×63 mm) and air-dried until the weightvariation from day to day reached less than 1% to give a pulp having awater content of 7.1% (Sample 1-1).

<Sample 1-2: Pelletized Oxygen-Delignified Pulp>

The compressed pulp described above was pelletized using a pellet press(a semi-dry continuous pelletization machine from TIGER-CHIYODAMACHINERY CO., LTD.) (9 mm in diameter×15 mm in length), and thenair-dried to give pulp pellets having a water content of 7.0% (Sample1-2).

<Sample 1-3: Unmolded Oxygen-Delignified Pulp>

The uncompressed oxygen-delignified pulp described above was directlyair-dried to a water content of 7.1% (Sample 1-3).

<Sample 1-4: Unbleached Kraft Pulp Dewatered in Two Stages>

The unbleached kraft pulp described above (having a consistency of about10%) was dewatered to a water content of 62.1% using a factory equipmentbelt press, and then dewatered to a water content of 26.9% using a screwpress (model SHX-200 from FUKOKU KOGYO CO., LTD.) (Sample 1-4).

<Sample 1-5: Unbleached Kraft Pulp Processed in a Paper Machine>

The unbleached kraft pulp described above was adjusted to a consistencyof 3% in a dissolving pulper, and then converted into a sheet in a smallpaper machine. The papermaking process comprises a wire part, a presspart, and a dryer part so that a sheet having a water content of 17.7%,and a basis weight of 123.5 g/cm² was obtained by adjusting the numberof passages through a drum roller controlled at a temperature of about100° C. in the dryer part. A 10×10 mm square piece was cut from theresulting sheet to prepare a feedstuff sample (Sample 1-5).

<Sample 1-6: Air-Dried and then Pelletized Unbleached Kraft Pulp>

The unbleached kraft pulp described above was air-dried to a watercontent of 17.9% and this pulp was molded into pellets using apelletizer from CPM to give pulp pellets having a water content of 13.9%(Sample 1-6).

Experiment 2: Determination of the Degree of Saccharification

A feedstuff sample obtained in Experiment 1 (compressed kraft pulp, 400mg on an air-dry basis) was precisely weighed into a resin sample vial(having a volume of 50 ml). Into the vial was added 45 ml of asuspension containing 0.1% of cellulase, pH4.8 (brand name: 102321Cellulase Onozuka R-10 from Merck & Co.) to saccharify the sample at 45°C. for 48 hours.

After 2 hours, 4 hours, 8 hours, 24 hours, and 48 hours, the sample wascollected and the proportion of the pulp saccharified (the degree ofsaccharification by cellulase) was determined. Specifically, the samplewas filtered on a filter paper preliminarily weighed after drying to aconstant mass, washed with water four times, and then dried in an aircirculation dryer at 135° C. for 2 hours, and the dry solids weight ofthe residue was determined.

The degree of saccharification by cellulase highly correlates withdigestibility in ruminants, and feedstuffs having higher degrees ofsaccharification are thought to be more easily digestible in ruminants.As shown in Table 1, Sample 1-1 (compressed kraft pulp) exhibited ahigher degree of saccharification and a higher saccharification rate ascompared with Sample 1-2 (pelletized oxygen-delignified pulp) and analmost similar degree of saccharification as compared with Sample 1-3(unmolded oxygen-delignified pulp). Sample 1-4 (oxygen-delignified pulpdewatered in two stages) and Sample 1-5 (oxygen-delignified pulpconverted into paper) exhibited almost similar degrees ofsaccharification to that of Sample 1-1.

TABLE 1 Time (h) 0 2 4 8 24 48 Sample 1-1 0.0 17.1 26.3 48.5 65.2 78.5Sample 1-2 0.0 17.9 26.9 49.3 62.8 67.3 Sample 1-3 0.0 15.9 24.4 42.669.3 80.2 Sample 1-4 0.0 16.8 27.1 47.5 66.3 78.2 Sample 1-5 0.0 15.324.5 43.2 61.8 75.4 Sample 1-6 0.0 16.5 25.8 46.2 63.4 68.5

Experiment 3: In Situ Evaluation of Digestibility

The samples prepared in Experiment 1 and commercially availablefeedstuffs (steam-flaked corn and bermudagrass hay) were analyzed fordigestibility in the rumen by an in situ method (Nocek 1988).

Into the rumen of a test animal (a dairy cow) were inserted polyesterbags (#R1020, polyester, 10 cm×20 cm, average pore diameter 50±15 μm,ANKOM Technology Corp., Fairport, N.Y., USA) containing 5 g of eachsample such as Sample 1-1 (compressed kraft pulp processed in a screwpress) weighed on an air-dry basis. At 2 hours, 4 hours, 8 hours, 24hours and 48 hours after the polyester bags were inserted, they wereremoved from the rumen, and washed with water, and dried to a constantmass at 60° C. to determine the dry solids weight. The same polyesterbags containing each feedstuff were prepared except that they were notinserted into the rumen but simply washed with water, and used assamples at a degradation time of 0 hour. Each sample was measured onthree different successive days.

The test results of each sample are shown in Table 2. As shown in Table2, the pulp of Sample 1-1 exhibited a digestibility higher than that ofbermudagrass hay. Moreover, the pulp of Sample 1-1 was digested moreslowly than steam-flaked corn, suggesting that it functions to inhibitsudden degradation and fermentation in the rumen.

TABLE 2 Evaluation of digestibility in the rumen Time (h) 0 2 4 8 24 48Sample 1-1 0.0 1.2 6.4 10.2 35.6 82.1 Sample 1-2 0.0 0.0 3.5 6.2 26.776.5 Sample 1-3 0.0 0.0 5.7 10.5 39.1 87.3 Sample 1-4 0.0 1.0 6.1 10.434.2 80.2 Sample 1-5 0.0 0.4 2.8 8.4 30.1 75.3 Sample 1-6 0.0 0.0 3.25.8 27.1 77.1 Steam-flaked corn 0.0 40.5 47.2 57.2 77.6 94.8Bermudagrass hay 0.0 23.5 25.4 30.2 46.7 61.3

Experiment 4: Feeding Preference Test

Four dairy cows (designated as A, B, C, and D) were allowed free accessto 300 g (on an air-dry basis) of the feedstuffs prepared in Experiment1 (Sample 1-1, Sample 1-2, and Sample 1-3) for 5 minutes. They were fedat 7:00 a.m., and a feeding preference test was performed three times inwhich the feedstuffs were placed at different positions each time.

As shown in the table below, Sample 1-1 exhibited a similar consumptionto that of Sample 1-3. However, Sample 1-2 (pellets) was inferior toSample 1-1 and Sample 1-3 in consumption probably because the animalsmay not be used to eating it.

TABLE 3 A B C D Average Sample 1-1 187 204 201 176 192 Sample 1-2 102 9454 62 78 Sample 1-3 214 184 195 203 199

Experiment 5: Determination of Volumetric Weight

The samples of Experiment 1 were dried to a constant mass at 105° C.Then, the weight and the volume were measured to determine thevolumetric weight.

As shown in the table below, Sample 1-1 (compressed kraft pulp) had avolumetric weight about 2.5 times higher than that of Sample 1-3,indicating that it has good transportability. Further, Sample 1-4 andSample 1-5 also have high transportability because they have volumetricweights increased by solid-liquid separation.

TABLE 4 Volumetric weight (g/L) Sample 1-1 354 Sample 1-2 623 Sample 1-3145 Sample 1-4 368 Sample 1-5 530 Sample 1-6 667

The oxygen-delignified pulp compressed in a screw press according to thepresent invention (compressed kraft pulp) exhibited a digestibility anda digestion rate almost comparable to those of the unmoldedoxygen-delignified pulp. Further, it tended to have a higherdigestibility than that of the pelletized oxygen-delignified pulp. Thismay be probably because it has not been compression-molded as in thecase of pellets and therefore, it is more rapidly soaked with digestivefluids. Moreover, the feedstuff had a higher bulk density and greatlyimproved transportability via a compression process using a solid-liquidseparator. Consequently, the feedstuff of the present invention wasexcellent in digestibility, transportability, and consumption.

1. A process for preparing a feedstuff for ruminants, comprising: suspending a lignocellulosic material as a raw material in a liquid to give a pulp; subjecting the resulting pulp to solid-liquid separation in a pressure type solid-liquid separator; and preparing a feedstuff containing the pulp subjected to solid-liquid separation.
 2. The process of claim 1, wherein the pulp has a water content of 45% by mass or more and less than 80% by mass after it has been processed in a solid-liquid separator.
 3. The process of claim 1, wherein the lignocellulosic material is derived from a wood resource.
 4. The process of claim 1, wherein the pulp is a kraft pulp.
 5. The process of claim 1, wherein the solid-liquid separator is a screw press and/or filter press.
 6. The process of claim 1, further comprising drying the pulp processed in a solid-liquid separator to a water content of 15% or less.
 7. The process of claim 1, comprising solid-liquid separation in multiple stages using a solid-liquid separator.
 8. The process of claim 7, comprising a first stage of solid-liquid separation until the water content of the pulp reaches 50 to 75% by mass.
 9. The process of claim 1, comprising solid-liquid separation using a paper machine or pulp machine.
 10. The process of claim 9, wherein the pulp subjected to solid-liquid separation using a paper machine or pulp machine has a water content of 15 to 35% by mass.
 11. The process of claim 1, further comprising pelletizing the pulp subjected to solid-liquid separation.
 12. The process of claim 11, wherein the pelletized pulp has a water content of 15% by mass or less.
 13. The process of claim 11, wherein the pulp has a water content of 15 to 30% by mass before it has been pelletized. 